This invention relates generally to apparatus for developing diazotype copy material and, more particularly, to apparatus which applies a liquid developing agent in metered amounts to exposed diazo copy material, thereby to produce dry-to-the-touch developed copies.
The method of developing diazo copy material by the application of relatively small, metered quantities of liquid developer is described in U.S. Pat. No. 3,446,620 and assigned to the same assignee.
Apparatus for carrying out the above method is disclosed in U.S. Pat. Nos. 3,626,833, 3,640,203 and 3,704,662, also assigned to the same assignee.
In the last-mentioned patent there is described developing apparatus comprising an applicator roller adapted to carry a limited quantity of developer fluid. A pressure applying blade is positioned adjacent the surface of the roller for engagement with the roller surface, and the area between the blade and roller surface forms a copy material developing zone. A second, fluid metering blade is also mounted for engagement with the roller surface at a position spaced 180.degree. from the first blade to equalize the forces applied to the roller. Developer fluid is supplied to the roller and is dispersed by the metering blade over the surface of the roller. The copy material is developed as it passes through the developing zone with the pressure blade applying pressure to the roller surface along a line of contact therewith equal to the force applied by the metering blade.
The foregoing described pressure-diazo process offers advantages over early types of diazo reproduction processes conventionally termed moist and ammonia or dry processes, as based on the conditions necessary to develop the exposed light-sensitive diazo material. The moist process requires the application of relatively large amounts of developing liquid, which are normally low in concentration of the active ingredients, and any excess liquid is squeegeed off and the sheet dried. Ammonia machines, which are used in the dry diazo process, require ventilation to the outside in order to remove the strong ammonia fumes. Consequently, these two well known diazo processes have certain inherent disadvantages over the pressure-diazo process referred to above, that detract from their being utilized more widely in office copying installations where the economics of the diazo processes are important and could be more fully realized.
The principal advantage of the pressure-diazo process is that the copy sheet emerges immediately after development in a dry-to-the-touch condition. Also, photocopying machines utilizing the pressure-diazo process are extremely simple to operate, substantially odor-free, and quite compact obviating the need for exhaust or drying equipment such as may be necessary to render the sheet sufficiently dry for handling as it emerges from the equipment.
However, while pressure-diazo machines offer certain advantages, they are unable to produce high volume reproduction and copies of a quality comparable to those of an ammonia diazo process. The present invention provides a developer apparatus for use with, for example, a machine as described in the above U.S. Pat. No. 3,704,662, which obviates the disadvantages of present day pressure-diazo machines and is capable of producing high volume reproduction and quality copies comparable to ammonia process diazo machines.